The present disclosure relates generally to fluid dispensing systems. More specifically, this disclosure relates to piston assemblies for a displacement pump of a fluid dispensing system.
Fluid dispensing systems, such as fluid dispensing systems for paint and other solutions, typically utilize axial displacement pumps to pull the fluid from a source and to drive the fluid downstream. The axial displacement pump includes a piston that reciprocates along a longitudinal axis to pump the fluid. Sealing rings surround the piston during operation and facilitate the creation of a vacuum condition in the displacement pump to allow the piston to pump the fluid. The sealing rings tightly interface with the piston, and the surfaces of the sealing rings experience wear due to the reciprocating motion of the piston. In addition, debris, such as grit or other solids in the fluid, can become lodged between the sealing rings and the piston. The debris can cause accelerated wear of the interfacing surface of the sealing rings, and the accelerated wear is often focused on one portion of the interfacing surface, causing asymmetrical circumferential wear. Asymmetrical wear leads to greater penetration of the fluid along the interfacing surface, and can lead to imbalance in the piston reciprocation and to the creation of bypass channels along the interfacing surfaces.